Name: skT45625 Date: 05/25/2000


1.3.0-C (HotSpot Client VM 1.3.0-C mixed mode)

We have our Swing app's mem leaks down to near zero (thanks for 1.3's
improvements!) with the exception of JMenuItem objs (& related objs) discussed
in this bug submission. It appears that new JMenuItems (for JInternalFrame
system menu L&Fs) are allocated every time a JInternalFrame is selected. It
can be a user titlebar click selection, or a programmatic one that setSelected
(true)s or toFront()s the JIF. Tracing down, it appears that the JIF's system
menu is rebuilt every time the JIF is selected.

The good news: Most of the JMenuItem related objs seem reachable (not able to
be gced) *only* until the JInternalFrame is closed (w/DISPOSE opt.).

The bad news: If the JIF is not closed, the JMenuItem stuff accumulates until
an out-of-memory condition occurs (the weak ref argument like that in:
http://developer.java.sun.com/developer/bugParade/bugs/4280094.html
does not appear to hold).

Using your favorite heap analyzer (I used OptimizeIT 3.1), run the hastily
constructed example code at end (using -Xms3M & -Xmx5M to show refs are not
released). Use MakeFrame to open a 3-5 JIFs & reset your heap obj counters.
Now click each of the JIF titlebars successively (or use Start Timer button to
spawn a Timer to do this) and watch the heap. The new 1.3 client hotspot gc
thread does a great job of reducing the heap, but ultimately the JMenuItem objs
will exhaust the heap.

If you close the JIFs, most of the JMenuItem-related objs will be released.

Granted, this is not as serious as it could be because most GUIs probably
result in JIFs being closed/disposed. In certain GUI designs, however, some
desktop JIFs may remain on the desktop for the entire session.

Once example is a lightweight/JIF progress monitor that is added to the desktop
and setVisible/toFronted during threaded/long processes. Its JIF is never
closed/disposed & every display (toFront) causes this heap condition. Another
example is our GUI where a row selection in one GUI causes several other JIFs
to be updated.... a JIF setSelected/toFront cascade cannot be used to inform
the users of the JIF updates due to this bug.

Example code (sorry for any cut&paste problems):

/* Demonstrates Selecting JIFs (causing toFront calls) causes lots of JMenuItem
related non-gced objects.
   Run with -Xms3M -Xmx6M to reduce heap to show that the objs are not gced &
an outofmem will occur.
   Shows apparent JMenuItem & related obj leakage under 1.2.X & 1.3.0 FCS for
L&Fs with System menus
   (mostly as long as JIFs are open... many JMenuItem objs are released upon
JIF close). */

import javax.swing.*;
import javax.swing.event.*;
import java.awt.*;
import java.awt.event.*;
import javax.swing.Timer;

public class JFrame1 extends JFrame {
    JDesktopPane desktop;
    static int frameCount = 1;

    public JFrame1() {
        super("JFrame Internal Frames Demo");
                          
        try { UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName
()); }
        catch (Exception exc) { System.out.println("Error loading L&F: " +
exc); }
                      
        final JSplitPane splitPane = new JSplitPane
(JSplitPane.HORIZONTAL_SPLIT);
                    
        final JDesktopPane desktop = new JDesktopPane();
        splitPane.setLeftComponent(new JLabel("Test"));
        splitPane.setRightComponent(desktop);
                        
        final JInternalFrame makeFrame = new JInternalFrame("Frame
Maker",true,false,true,true);
                          
        final JButton button = new JButton("Make Frame");
        button.addActionListener(new ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent event) {
                final JInternalFrame internal =
                    new JInternalFrame("Frame #"+
(frameCount++),true,true,true,true);
                internal.setDefaultCloseOperation
(JInternalFrame.DISPOSE_ON_CLOSE);
                internal.getContentPane().add(new JLabel
("Test"),BorderLayout.CENTER);
                internal.setBounds( frameCount*10 , frameCount*10 , 200, 150);
                internal.setOpaque(true);
                internal.setVisible(true);
                desktop.add(internal);
                internal.toFront();
splitPane.repaint();
}
        });
        makeFrame.getContentPane().add(button,BorderLayout.CENTER);
                    
        // Setup a hasty timer to simulate user JIF selects....
        final Timer warningTimer = new Timer(1500, new ActionListener() {
public void actionPerformed(ActionEvent evt) {
                final Component[] comps = desktop.getComponents();
                SwingUtilities.invokeLater( new Runnable() {
                    public void run() {
                        for (int k = 0; k < comps.length; k++) {
                            // all comps should be JIFs...
                            try {
                                JInternalFrame jif = (JInternalFrame)comps[k];
                                // Do not select JIF with MakeFrame
                                if (jif != makeFrame) jif.setSelected(true);
                            }
catch (Exception e) {
System.out.println("setSelected exception
e:"+e);
}
                        }
                    }
                });
}
        });
        warningTimer.setCoalesce(true);
        warningTimer.setRepeats(true);
            
        final JButton startTimer = new JButton("Start Timer");
        final JButton stopTimer = new JButton("Stop Timer");
            
        startTimer.addActionListener(new ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent event) {
if ( desktop.getComponentCount() > 1) {
warningTimer.start();
startTimer.setEnabled(false);
stopTimer.setEnabled(true);
}
else System.out.println("Only 1 JIF exists... Timer thread
NOT spawned");
}
        });
        makeFrame.getContentPane().add(startTimer,BorderLayout.NORTH);
                    
        stopTimer.addActionListener(new ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent event) {
warningTimer.stop();
startTimer.setEnabled(true);
stopTimer.setEnabled(false);
}
        });
        makeFrame.getContentPane().add(stopTimer,BorderLayout.SOUTH);
        
        makeFrame.setVisible(true);
        makeFrame.setBounds(200,0,200,120);
        desktop.add(makeFrame);
        getContentPane().add(splitPane,BorderLayout.CENTER);
        desktop.setSize(500,500);
                          
        getContentPane().validate();
        getContentPane().setVisible(true);
                 
        this.addWindowListener( new WindowAdapter() {
            public void windowClosing(WindowEvent event) {
                setVisible(false);
                dispose();
                System.exit(0);
            }
        });
        setSize(750, 560);
        show();
    }
    public static void main(String args[]) {
        new JFrame1();
    }
 }

icsbug
(Review ID: 105277)
======================================================================